Fiber glass batches, unlike soda-lime glass batches and other commercial batches utilized to make containers and flat glass, are fed to fiber glass melting furnaces in an extremely fine condition, i.e., almost all batch particles are less than 20 mesh, with the majority being less than 200 mesh. Because of the fineness of the batch ingredients, dusting is encountered in fiber glass batch melting furnaces. In addition, fiber glass batches contain considerable quantities of boron-containing materials and other rather expensive ingredients, some of which are lost in the stack gases should dusting occur during feeding. Further, some of these batch materials volatilize into the stack gases as they are melted. By cohesively binding batch ingredients of the fineness normally encountered in a fiber glass batch, reduced dusting and volatilization of the batch ingredients and the concomitant reduction in the loss of expensive ingredients can be achieved. In addition, by providing fiber glass batch in pelletized form, advantage can be taken of the sensible heat contained in the furnace flue gases to preheat the fiber glass batch pellets prior to feeding them to the glass melting furnace. Further, the close contact between the particles within the pellets improves their heat transfer characteristics and thus results in faster melting, improved energy efficiency and reduced furnace wear.
Considerable activity has taken place in recent years and particularly in relation to the preparation of soda-lime glass batches in which the batch ingredients have been pelletized for feed to glass melting furnaces. Thus, a recent U.S. Pat. No. 3,880,639 describes the utilization of an agglomerated soda-lime glass batch in which the pellets are preheated via direct heat exchanges prior to feeding them to a glass melting furnace.
Activity has also occurred in the preparation of fiber glass batches in that glass batches have been prepared with various binding materials for the preparation of briquettes for feeding to glass melting furnaces. U.S. Pat. No. 2,976,162 describes a process of this nature. In other patent literature involved in the preparation of fiber glass type batches, special treatments have been applied to the glass batch to provide for prereaction of glass batch ingredients prior to feeding them to the glass melting furnace. A process of this character is described in U.S. Pat. No. 3,001,881. Still further, the glass batch ingredients themselves have been carefully selected to provide boron-containing glass batch materials of specific character to help eliminate some of the foaming problems occurring during melting utilizing high boron-containing glass batches such as are encountered in the fiber glass industry. A patent describing one such process is U.S. Pat. No. 3,287,095.